A planar inverted F antenna has been proposed as an antenna advantageous for use with a portable wireless apparatus such as a mobile telephone. For example, in an antenna disclosed in US Patent Application No. 2012/0092226, a slot acting as an antenna is formed between two portions of a ground electrode. Further, an antenna element is connected via one terminal to one of the two portions of the ground electrode and is fed via that terminal, and the antenna element is grounded via another terminal to the other of the two portions of the ground electrode.